Wastewaters may be treated and purified in many different ways. One way to purify waters is to use membrane bioreactors. A process using membrane bioreactor (MBR) combines membrane filtration technique with biological treatment of wastewater. The membrane is a barrier that only allows certain components to pass through it, the permeate. The selectivity of the membrane may be controlled by its pore diameter. The suspended solids and micro-organisms of the biological treatment are separated from the treated water by using suitable membranes, e.g. ultrafiltration or microfiltration membranes. The membranes may be immersed in the biological reactor tank, i.e. integral with the biological reactor tank, or the membranes may be arranged outside the biological reactor in a separate process unit, whereby an intermediate pumping step may be required.
MBR processes may have problems with membrane fouling, which reduces flux through the membrane. Membrane fouling may be due to blockage due to particle sizes or the interaction between the membrane material and the activated sludge liquor comprising living and/or dead micro-organisms, colloidal materials, soluble compounds, etc. To prevent membrane fouling air sparging of the membranes and regular backwashing may be performed. Chemical cleaning of the membranes is also a solution to this. Such steps provide drawbacks as increased process costs, energy consumption and membrane downtime, etc.
It would be desirable to find new ways which allows for better interaction between the used components to reduce defects and drawbacks arising due to their interaction.
There is a demand of solutions for improving membrane performance and water treatment efficiency in a cost effective and environmentally friendly manner.